Oregon Department of Environmental Quality
June 1988
Wacker Siltronic Corporation is a semi-conductor manufacturer which has made hazardous waste minimization a top corporate priority. "It's been a real eye-opener," says Murray Tilson, Environmental Manager. Through recycling programs and process changes implemented in early 1986, "Wacker went from 1.3 million pounds of 'cradle to grave' liability a year to 26,000 pounds -- a 98 per cent waste reduction." These operational changes and the recycling program cost Wacker approximately $50,000 to implement. They save the company $300,000 annually.
The firm began to investigate waste minimization alternatives when federal regulations eliminated the option of disposing chlorinated solvent wastes at the Arlington, Oregon hazardous waste disposal facility. At first, Wacker used off-site recycling services, but the liability nightmare of transporting thousands of gallons of solvent to a recycling firm made Tilson seek alternatives.
Since cleanliness is the #1 priority in silicon wafer production, "When a problem would develop, we'd refill the solvent baths to correct ft." Material and disposal costs weren't considered especially important before management approved a six-month pilot program to decrease the use of chlorinated solvents.
Process, manufacturing, and equipment engineers and suppliers tackled the problem with the help of Wacker staff in Burghausen, Germany. They found that using thousands of gallons of chlorinated solvent wasn't the answer to quality control. Careful process monitoring and control reduced the number of baths by a factor of 15 In one major process system alone.
Taking the waste minimization concept one step further, in June 1988, Wacker completely eliminated the use of chlorinated solvents by modifying the cleaning process to use a nonhazardous product.
"Everybody wins, nobody loses," says Tilson.
Prior to 1986, Wacker sent 2,000 gallons of chrome VI wastes to Arlington each month. 'That meant a 24,000 gallon liability every year. It was a major concern," Tilson adds.
The solution was three-fold -- and simple. Wacker first installed are in cover over the outdoor tanks at a cost of $7,000. This kept rainwater out of the holding tanks and reduced hazardous waste shipments to Arlington by 25 per cent. Then Environmental Engineer Greg Carr searched for water leaks in the process rinse tank. He found a "small leak" that resulted in a 50 per cent reduction in waste production.
When additional regulations prohibited storage of liquid chrome VI wastes at Arlington, Wacker began on-site waste treatment. The new treatment system uses caustics and sodium bisulfite to reduce chrome VI liquid to less hazardous chrome III sludge. The neutralized sludge is stored in 55-gallon drums which are dried with wraparound heaters before being shipped to Arlington.
The rain cover, pipe repairs and on-site waste treatment system cost Wacker $30,000 and resulted In a 95 per cent reduction in chromic wastes, as well as annual savings in disposal costs of $15,000.
"We went from 6,000 gallons to two or three drums every quarter," says Tilson. The initial investment cost was recouped in three years.
Concern for quality control was also the reason for Wacker's high usage of Freon 113, one of the most expensive solvents used in the electronics industry today. (Freon is a registered trademark of E.I. DuPont de Nemours & Company, Inc.)
Carr converted an open-top still to recycle the Freon as part of a closed loop system. The conversion decreased waste volume by 85 per cent and cost $20,000. Every year it saves Wacker almost $57,000.
Each batch of recycled Freon is tested rigorously for problem-causing water, denatured ethanol, and particulates. 'We conduct the same ASTM tests on our recycled product that we do for incoming virgin material. In all cases, the results meet or exceed the specs established for virgin Freon," says Carr.
Warns Tilson, "The hi-tech industry is changing all the time. We have to stay on top of the changes and we're convinced waste minimization is a tremendous benefit to our company."
Your company need not be a corporate giant to benefit from the waste minimization technology used at Wacker Siltronic. All it takes is a commitment to excellence and the willingness to ask for help. DEQ would like to be part of your company's solution to the hazardous waste problem.
Profile Is produced and distributed by the Hazardous Waste Reduction Program of the Oregon Department of Environmental Quality (DEQ).
Oregon Department of Environmental Quality
811 SW 6th
Portland, OR 97204
or call (503) 292-5913.
Outside the Portland area within Oregon call 1-800-452-4011.
June 1988
Last Updated: November 22, 1995